What makes a "smog" carburator?

P

Patrick Morris

Member
I was just curious why the 2210 replaced the 2300 on IH and presumably other engines during the 1970s. What was it about the 2300 that prevented it from enabling sufficiently low emissions? And why was the 2210 better suited for the job? Anyone know?
 
I do not know the exact reason for the 2300 to 2210 Holley change.

But, it probably came down to "money"...

Carbs had to be "modified" to run leaner at idle -- very simple "explanation".

Us manufacturers addressed the problem in a "piecemeal" manner (my opinion).

There were a number of ways to get a carb to run leaner at idle -- modify the existing carb, build a new carb, use a different carb or modify a different carb.

In the case of corvairs, "GM" modified the existing rochester hv carb by adding an "idle air bleed circuit" (a change to the body / casting of the carb - not really cheap) which added additional air at idle (I believe) using a "metering orifice" with an additonal passage in the carb body (for 68 - 69 model years - cannot remember about CA -- CA corvairs "required" a smog pump in 1966).

Also, I believe the venturi cluster was also changed -- carb is a bit different than a Holley, etc

hth
 
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